Not applicable.
Not applicable.
The invention relates to a stripping machine for optical or electrical conductors, in particular for coaxial cables, and a process for length measurement. European Patent Application EP-673099-A2 describes such a stripping device having clamping jaws, centering jaws and rotating blade devices. What is described in said European Patent Application as a preferred or advantageous measuring process, namely the measurement of the length of an inserted conductor end piece, can in practice have disadvantages. The process described in the Patent Application essentially comprises the axial holding of the cable end by means of the clamping jaws, closing the centering jaws up to the external cable diameter, whereupon the centering jaws remain pretensioned under a spring load on the external cable diameter, and the final, axial displacement of the centering jaws up to the end of the cable end, where the centering jawsxe2x80x94as intended in the Patent Applicationxe2x80x94close against one another under the spring force, which then leads to signal output from a pressure sensor.
However, this method can be disadvantageous precisely in the case of thin cables for which the present solution is mainly intended, in particular with soft outer sheaths, since, under the friction between centering jaws and outer sheath, the latter can be axially displaced relative to the inner layers of the cable, so that the sheath projects slightly beyond the conductor at the cable end, with the result that incorrect length detections may occur. In addition, the shielding may be damaged by the centering jaws of the known design during the stripping process, said centering jaws being acted on by a force.
The first object of the invention is to provide an improved length measuring process for cable ends in stripping machines.
The object is achieved by the following:
A process for operating a cable stripping device, having at least one of clamping jaws, axially displaceable blade jaws and centering jaws on a carriage with a controlled drive and at least one contactless sensor, the sensor being provided directly adjacent to at least one of the blade jaws and the centering jaws, including the following steps: fixing the end of the cable, after it has been inserted, by the clamping jaws in its processing position, gripping the cable end with at least one of the blade jaws or centering jaws on its outer sheath and centering said cable end, wherein the blade jaws or centering jaws satisfy at least one of the following conditions: at least one of the blade jaws and centering jaws: a) are positioned a small radial distance from the surface of the cable, the cable diameter being known; b) are applied to the cable surface with at least one of a small incidental force or without force; c) are raised from an applied state to a state in which they are applied to the cable surface with at least one of without force, a small incidental force and to a raised state, so that at least one of the blade jaws and centering jaws still hold the cable in a relatively centered position which satisfies at least one of the following conditions: without force and with a small incidental force, and moving at least one of the centering jaws and the blade jaws in an axial direction to the cable end, the presence of the inserted cable end being detected during the movement step, the actual cable end thus being detected in a contactless manner by the contactless sensor for further controlling operation of the stripping device.
The actual length of the cable end is thus determined, according to the invention, by detecting a certain axial displacement of the centering or blade jaws relative to the cable end (as known per se, but now with the jaws in a partly raised state or with jaws applied without force or with a small incidental force) from a defined position in the vicinity of the clamping jaws to the cable end, the insertion of a cable and reaching of the cable end with scanning being detected by a contactless, preferably optical sensor, which thus ends the measurement of the length of the displacement of the centering or blade jaws.
According to the invention, there are essentially three variants:
a) The centering and/or blade jaws are positioned a small radial distance from the cable surface, the cable diameter being known (by prior input of this value).
b) The centering and/or blade jaws are applied to the cable surface without force or with a small incidental force.
c) The centering and/or blade jaws are raised from an applied state to a state in which they are applied without force or with a small incidental force or to a raised state.
In the context of the invention, xe2x80x9csmall forcexe2x80x9d is understood as meaning a force which unintentionally occurs when an article (jaw) comes into contact with another article (cable), although it is not intended that one article rests against the other under the action of force. In any case, this small force is so small that, during a displacement of the two articles (jaw and cable) relative to one another, one article certainly has no interfering mechanical effect on the other.
A further object of the invention is to provide a process for operating a stripping device. This object is accomplished by the following process:
A process for operating a stripping device having clamping jaws blade jaws, and centering jaws, including the following steps: measuring the difference in cable length between an inserted cable end and a desired insertion length, gripping a cable by at least one of the blade jaws and the centering jaws at a position reflecting the difference in length as determined by measuring the length of the cable end, between the length of the inserted cable end and the desired insertion length, and displacing the cable in the axial direction to a desired axial cable end position, the clamping jaws releasing the cable during displacement of the cable.
In this process, the centering and/or blade jaws are preferably in the vicinity of the clamping jaws or are moved into the vicinity of the clamping jaws to begin centering the cable there or to begin the length measurement. This is advantageous, inter alia, because the clamping jaws themselves are generally also designed for centering and the cable can thus be readily enclosed there.
Optical sensors are nothing new in connection with stripping devices. Thus, Schleuniger Holding AG used stop sensors for cable ends as long ago as 1986, some of which sensors contain an optical light system in the sensor part for detecting a completed stop or the resultant small displacement of a sensor rod.
Komax has published, under the type number 324, a device which has an optical system and which is able to determine the stripping state of an already stripped cable in order thus to produce a signal or error message with digital processibility. In the European Patent Application mentioned above, the use of a light barrier is also proposed, which however is formed or intended only for the rough alignment and optical scanning of a conductor end section to be processed. Its function thus corresponds approximately to the above-mentioned function of the optical sensor in the stop sensor from Schleuniger. This sensor interacts with a sensor rod to indicate the arrival of a cable end.
However, optical sensors have not been used to date in cable processing for the measurement of the length of cables or cable ends.
The advantage over the known solution is that, in spite of relatively good centering (the cable can rest under its own weight gently against a centering or blade, e.g., V-blade jaw, damage to or displacement of a length of the sheath of the conductor is avoided and an exact determination of the conductor end is therefore possible. The optical sensor system preferably used according to the invention in this context thus permitsxe2x80x94in interaction with a conventional length-measuring devicexe2x80x94an exact measurement of the length of the conductor end piece from a starting point to the actually determined conductor end, along the axial displacement of the jaws, butxe2x80x94owing to the opening of the jaws in accordance with the inventionxe2x80x94does so without producing errors due to frictional forces between jaws and cable.
Particular further developments and embodiments and variants of the invention are described and protected in the dependent claims.
An embodiment of the invention, which as such can also be used independently permits the mechanical and automatic adjustment of the cable end length to a desired value so that the correct (desires) length can be stripped even in the case of flexible cables and with inexact or manual introduction of such cables into a stripping machine. Such embodiment has the following features: A control includes a program and an input unit, to input a desired cable end axial position in the input unit, and wherein, if a set cable end axial position does not agree with the cable end position actually measured, the program actuates the clamping jaws and at least one of the centering jaws and blade jaws alternately, so that at least one of the blade jaws and centering jaws clamp the cable and displace the cable in the axial direction to the desired axial position while the clamping jaws open at least slightly to release the cable for displacement.
By means of a preferred particular control, the jaws are held in a plane, for example a horizontal one, so that it is possible to introduce from above a conductor which interrupts the light barrier and thus triggers the clamping jaws. The clamping jaws close and hence themselves produce a certain centering. In this case, the light barrier can also be arranged between clamping jaws and centering jaws.
Conventional light barriers, optionally also reflection sensors, may be used as the light barrier.
With regard to the resolution in the fine range, however, light barriers are recommended. For example, a light barrier xe2x80x9cDL 20 or DLM 30xe2x80x9d from STM Sensortechnologie, Mxc3xcnchen GmbH could be used for an embodiment. With a standard amplifier, a resolution of 0.2 mm cable diameter can be achieved with these light barriers. For even finer resolution or optionally also for detecting stripping stages, said light barriers can be further improved with a high-resolution amplifier so that the resolution increases with a wire diameter of less than 0.05 mm. In the embodiment, the types V6/V7 for standard resolution or V62/V72 for high-resolution amplification from said company STM could therefore be used as amplifiers.
In the present application, reference is constantly made in particular to centering or blade jaws. However, structures which are not based exclusively on jaws but, for example, also comprise centering or stripping devices which are other than jaw-like are also within the scope of the invention. For example, funnel-like devices can also be used for the centering and laser blades, disc-like blades rotating about their own axis, or the like, can also be used for the cutting.